1. Field of the Invention
This invention relates to the field of image projectors and more specifically an image projecting having a tubular telescoping body that is telescopically collapsible into an object with a small stowage footprint.
2. Discussion of the Prior Art
Image projectors using fully colour capable LCD systems require small but high-intensity light sources to adequately project images on a distant screen. Light sources such as xenon, halide or arc lamps are often used. Examples of such projectors include U.S. Pat. No. 6,224,216 xe2x80x9cSystem and Method Employing LED Light Sources for a Projection Displayxe2x80x9d issued to Parker and Peterson on May 1, 2001; and, U.S. Pat. No. 5,820,242 xe2x80x9cCompact Integrated LCD Projectorxe2x80x9d issued to Rodriguez and Haushalter on Oct. 13, 1998. Both of these inventions rely upon forced air-type cooling systems generally comprising a heat sink in the form of air filled voids and a fan/motor combination to circulate air and dissipate heat through vents in the body of the projector. Image projectors of this type are necessarily voluminous to accommodate the required air voids for the cooling system and tend to retain a rectangular shape. Neither example of existing projectors is collapsible to the extent possible by utilizing heat sink air voids as stowage space.
Therefore, there continues to be a need for an image projector that is smaller, more portable and with a reduced foot print when operating and stowed for transport that takes advantage of unused heat sink voids as stowage space.
In light of the disadvantages noted above, it is a principle object of the present invention to provide a telescopically collapsible projector.
Another object of this invention is to provide a telescopically collapsing projector that can be substantially reduced in size for stowage while retaining the ability to produce clear, undistorted images on a projection screen.
It is a further object of the invention to provide a compact, telescopically collapsible projector that utilizes electronically addressable colour LED technology capable of taking image signals from a computer and projecting them on a distant screen.
It is yet a further object of the present invention to provide a telescopically collapsible projector that has a reduced operating and stowage footprint while retaining the ability to adequately air cool the heat producing components of the projector during operation.
Another object of the present invention is to provide for a telescopically collapsible projector that can take advantage of cool light source technologies.
The objects are achieved by providing a telescopically collapsible image projector having a segmented tubular body comprising:
a. a first tubular body segment;
b. a second tubular body segment co-axially mounted to the first tubular body segment and adapted for sliding concentric placement within the first tubular body segment; and,
c. a third tubular body segment co-axially mounted to the second body segment and adapted for sliding concentric placement within the second tubular body segment.
The image projector has a first stowed configuration in which the first, second and third tubular body segments are co-axially and telescopically collapsed within each other in concentric placement; and, a second operating configuration in which the first, second and third tubular body segments are co-axially deployed thereby forming a rigid optical pathway.
The image projector further comprises means for supporting the first tubular body segment, second tubular body segment and third tubular body segment co-axially in the second operating configuration; means for projecting an image on to a distant projection screen; means for cooling the image projector; and, means for controlling the image projector.
The first tubular body segment comprises: a closed back end; an open front end having an edge; an outer surface having an outer diameter; and, an inner surface having an inner diameter wherein the closed back end, the open front end, the inner surface and the outer surface act together to form a void. The void is adapted to receive the second tubular body segment and the third tubular body segment in respective concentric placement. The first tubular body segment further includes a flange depending radially inwards from the open front end edge. The flange has a bearing surface, a rear surface and a front surface.
The second tubular body segment comprises: an open back end having an edge; an open front end having an edge; a length; an outer surface having an outer diameter; and, an inner surface having an inner diameter wherein the open back end, the open front end, the outer surface and the inner surface act together to define a lumen. The lumen is adapted to receive the third tubular body segment in concentric placement. The second tubular body segment furthering includes: a first flange depending radially outwards from the open back end edge. The first flange has a front surface, a back surface and a bearing surface. A second flange depends radially inwards from the front end edge. The second flange has a front surface, a back surface and a bearing surface. The second tubular body segment further includes: a plurality of apertures spaced radially about its outer surface; and, a first mounting hole and a second mounting hole distally positioned at the open first end. The first mounting hole and the second mounting hole are positioned opposite each other.
The third tubular body segment comprises: an open back end having an edge; an open front end having an edge; a length; an outer surface having an outer diameter; and, an inner surface having an inner diameter wherein the open back end, the open front end, the outer surface and the inner surface define a lumen. The third tubular body segment further includes a flange depending radially outwards from the first open end edge. The flange has a back surface, a front surface and a bearing surface.
The image projector also includes means for supporting the first tubular body segment, second tubular body segment and third tubular body segment co-axially when the projector is in its operating configuration. The support means comprises means for supporting the second tubular body segment within the first tubular body segment and means for supporting the third tubular body segment within the second tubular body segment. These means comprise a first, second, third and fourth support. The first support comprises the bearing surface of the second tubular body segment first flange being in sliding frictional contact with the inner surface of the first tubular body. The second support comprises the bearing surface of the first tubular body segment flange in sliding frictional contact with the outer surface of the second tubular body. The third support comprises the bearing surface of the second tubular body segment second flange in sliding frictional contact with the outer surface of the third tubular member. The fourth support comprises the third tubular body segment flange bearing surface in sliding frictional contact with the inside surface of the second tubular body segment. These supports act together to permit telescopic co-axial sliding movement between the second tubular body segment and the first tubular segment and co-axial sliding movement between the second tubular body segment and the third tubular body segment. Hence the imaging projector may be moved from its first stowed configuration to its second operating configuration and form a rigid optical pathway. Additionally, the supports permit movement from the second operating configuration to the first stowed configuration.
Means for projecting an image on to a distant projection screen comprises the rigid optical pathway which is defined by the axis of the first tubular body segment, second tubular body segment and third tubular body segment co-axially aligned in the second operating configuration. Also included is a projection light source positioned on the optical pathway for illuminating an image for projection, a diffusing filter positioned adjacent to the light source on the optical pathway for diffusing light from the projection light source, an imaging element positioned on the optical pathway adjacent to the diffusing filter for creating images for projection and image focusing means for focusing projected images on to a distant projection screen. The projection light source comprises a device selected from the group consisting of filamented bulbs, arc lamps, fluorescent lamps, and light emitting diodes. The projection light source is mounted within a parabolic mirror. The mirror is in turn mounted to a circular frame that is mounted to the inside surface of the first tubular body segment. The frame further includes a plurality of apertures set radially at its distal periphery. The diffusing element is mounted between the projector light source and the imaging element within the first open end of the second tubular body segment. The diffusing element further comprises a plurality of apertures set radially at its distal periphery. The imaging element is mounted within a frame that is in turn mounted to the inside surface of the second tubular body segment by two co-axial pins. Each of these pins is mounted on opposite sides of the frame and adapted for insertion and rotation within mounting holes in the first end of the second tubular body segment. These pins permit the frame and imaging means to pivot for keystone correction of the projected image. The frame has an outside diameter less than the inside diameter of the second tubular body segment so that an annulus is formed permitting air flow between the frame and the inside surface of the second tubular body segment. Preferably, the imaging element is a fully colour capable single liquid crystal display. However, this invention contemplates the use of one of a plurality of monochromatic element liquid crystal displays, micro electrical mechanical systems, light valves, suspended particle devices, polysilicon displays, liquid crystal on silicon displays, and interferometric modulators. The image focusing means comprises a focusing tube with a focusing lens that act and move in combination. The focusing lens is mounted within the second open end of the third tubular body segment and is co-axial with the optical pathway. The focusing tube is capable of axial movement towards and away from the imaging element by frictionally sliding the focusing tube in and out of the second tubular body segment thereby applying focusing correction to a projected image. In an alternative embodiment of the invention, the focusing tube is threadably mounted within the second tubular body segment so that the focusing tube may be moved into and out of the second tubular body segment by rotating the focusing tube about its axis in a clockwise and counterclockwise direction. In yet another embodiment of the invention, the focusing tube is slideably moveable into and out of the second tubular body segment using rack and pinion gear system. The rack may be fixed to the outside surface of the focusing tube and operated in meshed cooperation with the pinion gear that is fixed to the inside surface of the second tubular body segment.
When the image projector is in its first stowed configuration, the entire length of the second tubular body segment is positioned concentrically within the first tubular body segment and the entire length of the third tubular body segment is positioned concentrically within the second tubular body segment. As well, the inside surface of the second tubular body first flange abuts against said circular frame of the projection light source and the inside surface of the third tubular body segment flange abuts the imaging means frame.
To dissipate heat generated by the projection light source, the image projector further includes means for cooling the image projector comprises a cooling system comprising a heat sink adjacent to the projector light source for absorbing heat the projector light source; an aperture in the centre of the closed end of the first tubular body segment for exhausting heated air; a plurality of apertures radially displaced about second tubular body segment for drawing cooling air into the image projector; and, a fan housing support mounted over the aperture adapted for mounting an electric fan/motor assembly that is capable of drawing cooling air from the plurality of apertures in the second tubular body segment and exhausting heated air from closed end aperture of the first tubular body segment.
The heat sink comprises an air-filled void adjacent to the projector light source that is formed when the segmented tubular body of the image projector is extended to its second operating configuration. When the image projector is in its stowed configuration, the air void becomes a storage chamber for the second tubular body segment and the third tubular body segment.
The image projector has control means comprising a plurality of control circuits that are adapted to operate and control the electrical and mechanical components of the projector. The control circuits are mounted to a circular circuit board that is apertured at its centre for cooling air flow. In various embodiments of the invention, the control circuit includes digital image conversion means, memory means, voice actuation and control means, digital processing means, means for audio-visual presentations and means for remote operation the image projector.
The projector further includes a circular body cap adapted to fit over the end of the projector when the projector is in its stowed configuration. The cap includes a supporting member adapted to support the third body segment when the projector is in its operating configuration. Hence the cap provides a stable support to the projector on flat surfaces.